The HypoG-01 study (UNICANCER) is a French multicenter, randomized, phase 3, open-label, non-inferiority study of 5-year results of hypofractionated locoregional radiotherapy in early breast cancer.[1] It included 1265 patients with T1–3, N0–3, M0 breast cancer requiring nodal irradiation, randomized 1:1 into two groups.[1][2] The first group received 40 Gy in 15 fractions over 3 weeks, the second 50 Gy in 25 fractions over 5 weeks, with the possibility of a boost in both.[1][2] The primary endpoint was the 3-year cumulative incidence of shoulder lymphedema, which was approximately 33% in both groups.[1] A study has shown that 3 weeks of radiotherapy is non-inferior to 5 weeks in terms of the risk of lymphedema and is comparably safe with regard to other late tissue effects.[1] In the postoperative population, there were 562 patients in the hypofractionated group and 551 in the standard group.[1] Initial adverse events were mild and did not raise safety concerns for 3 weeks of radiotherapy.[2]